Automatic focusing device for cameras.



F. M. STEADMAN.

AUTOMATIC FOCUSING DEVICE FOR CAMERAS.

APPLICATION FILED NOV. {0. 1914. 1,244,254. Patented Oct. 23,1917.

2 SHEETS-SHEET l.

F. M. STEADMAN,

AUTOMATIC FOCUSING DEVICE FOR CAMERAS. APPLICATION FILED NOV. 10. 1914.

1,244,254. v A Patented Oct. 23,1917.

WITNESSES /Nl/ENTOR -76? 980A 3/ Q r412? W By ATTORA/EYS FRANK M.STEADMAN, OF WASHINGTON, DISTRICT OF COLUMBIA.

AUTOMATIC FOCUSING DEVICE FOR CAMERAS.

Specification of Letters Patent.

Patented Oct. 23, 1917.

Application filed November 10, 1914. Serial No. 871,282.

To all whom it may concern:

Be it known that I, FRANK M. STEADMAN, a citizen of the United States,and a resident of Washington, in the District of Columbia, have madecertain new and useful Improvements in .Automatic Focusing Devices forCameras, of which the following is a specification.

My invention relates to improvements in automatic focusing devices forcameras, and it consistsin the combinations, constructions andarrangements herein described and claimed.

An object of my invention is to provide a device by means of which acamera may be accurately and automatically focused, thereby obviatingthe danger of spoiling the plate or film by neglect to set the camera atthe proper focus.

A further object of my invention is to provide a device of the typedescribed which may form an attachment for a camera having an extensiblebellows and a movable lens.

A furtherobject of my invention is to provide a device of the typedescribed having a flexible member which may be extended manually fromthe camera to the object to be photographed and in which the movement ofthe flexible member serves to bring the device into focus.

Other objects and advantages will appear in the following specificationand the novel features of the device will be particularly pointed out inthe appended claims.

My invention is illustrated in the accompanying drawings forming part ofthis application in which- Figure 1 is a plan view of a camera providedwith my improved automatic focusing device, showing the latter in oneposition,

Fig. 2 is a view similar to Fig. 1 showing the apparatus in a shiftedposition,

' Fig. 3 is a section along the line 3-3 of Fig. 2 y

Fig. 4-. is a section along the line 4-4 of Fig. 2,

Fig. 5 is a plan view of a portion of the evice, certain parts beingbroken away for the sake of elearness,

Fig. 6 is a view of a modified form of the device, v

Fig. 7 is 'a plan view, ofa portion of the apparatus shownin Fig. 6,

Fig. 8 is a view similar to Fig. 7 showing the aparatus in anotherposition, and

Fig. 9- is a section along the line 9-9 of Fig. 7.

In carrying out my invention 1 may make use of a camera known as thedrop-front type, that is to say in which the case 1 is provided with ahinged door 2 which may be dropped downwardly and which may be held inposition by braces 3. In this type of camera the bellows 4 may beextended by pulling the lens frame 5 forwardly. The latter is mounted ona slidable extension 6 which may be moved relatively to the door 2 ashereinafter explained. The door 2 is provided with a scale over which apointer 7 is designed to move. The lens frame 5 may be pulled out andthe pointer 7 moves with it so that it may be set at a figure on thescale which gives the proper'focus. The description of the device thusfar concerns the ordinary camera and forms no part of my inventionexcept in so far as the parts hereinafter enumerated to eflect a new anduseful result.

Referring now particularly to Figs. 3, 4 and 5 I have shown therein atransverse rod 8 which is revolublv mounted in the door 2 and which isprovided with threads 8 at its central portion as clearly shown in Fig.4. One end of the rod 8 is provided with a collar 9 which bears on aside plate 9 so as to prevent any longitudinal movement of the rod.

The door 2 is provided with a transverse slot 10 in which is disposed athreaded block or nut 11 having a pin 12 projecting therefrom. Theopposite end of the rod 8 is extended and a reel 13 is secured to theextension, a collar 14 being provided between the reel and the door 2,as shown in Fig. 4:. Upon the reel is wound a flexible strip 15, afterthe manner of a tape measure, an opening being provided in the casing ofthe reel for permitting the entrance andexit of the flexible member 15,while a spring (not shown) may also be provided'for taking up the slackwhen the end of the flexible member 15 is moved toward the camera, afterthe manner of an ordinary tape measure holder.

The bottom of the extension 6 is provided with a plate 16 having acurved cam surface 16 which is arranged to engage the pin 12. A spring17 is connected at one end to a downwardly extending arm 18 on the endof the extension 6am], at the other end is provided with a hook 19 whichmay be secured to an eye 20 or other suitable fastening means onthe'outside of the door 2 as will be hereinafter explained.

From the foregoing various parts of the device the operatlon thereof maybe readily understood.

I shownin Fig. 1.

The operator now takesholdof the end of the extension 6 and pulls thelatter downwardly until the pin 12 in the block 11,

which, when the tape or flexible member 15.

is retracted, is in 'alinement with a slot 10" running longitudinally ofthe extens on 6 (see Figs. 1', 4 and 5) now comes in registration with aslot 22 extending at right angles to the slot 10". In order to gage thedistance to which the extension 6 must be moved and inorder to bringthe'slot 22 into registration with the pin 12 I pull the extension outuntil the pointer 7 registers with the onemeter mark or any otherpredetermined close distance mark when the slot 22 will be just oppositethe pin. If now the flexible member or tape'15 be pulledoutwardly therotation of the spindle 8' will cause the block or nut 11 to travel fromthe left to the right,

as shown in Figs. 2 and 4. When the pin 12 enters the slot 22 the spring17, which, up to this time has been free, that is to say it has beensuspended from the arm 18 only,

is now connected with the eye 20 by stretching the spring and placingthe hook 19 in the eye. This will put the extension 6 under springtension which tends to pull it in-.

. wardly into its normal position, but it is prevented frommoVement-bythe pin 12 in the slot 22.

The tape or flexible member 15 may now be moved outwardly toward theobject. first movement of one meter (which includes the movement tovadvance the pin into the .slot 22) merely causes the pin to travel tothe end of the slot 22, but beyond one meter the movement of the pin nowpermits the cam surface 16" to engage the pin and as the lattercontinues to move the extension 6 will be retracted by means of thespring 17. The

cam surface 16 is curved or cut in such a fashion that the extensionwill be retracted so as to always keep the device in focus. Thus, if thetape is pulled out to a distance of fifteen feet theextension will beretracted until the pointerregisters with the mark 15 on the door of thecamera. If the tape is description of the that if one The pulled outtwent .-five feet, it is obvious that the retraction wi be ater and thepointer will be atthe numera 25 on the scale. The

formation of the cam surface 16* is deter-- mined by calculation orexperiment so as to accurately focus the device for any object withinthe limits of the focusing scale, so

the camera is automatically brought to the proper focus for that object.Thetape may now be dropped or placed to one slde out of the field ofview, the catch (not shown) .in the tape casing 13 preventing theretracby causing the tape to retract in the ordimanner, the extension 6being first pul ed outwardly to permit the movement 'of the pin-12 againthrough the slot 22 and into the slot 10*, when the device may be foldedas. in the usual manner.

In Figs. 6 to 9 inclusive I have shown a modified form of the deviceconsisting of an attachment for the ordinary drop-front camera. In thisinstance the door 2 is provided with a scale 6 over which a pointer 7carried by a slidable lockin device 21 having a latch or looking ever21, is arranged to travel, as shown in Fig. 6. In the ordinary cameranot provided with my attachment the lens frame 5'? to which the lockingmember 21* is secured is pulled forwardly until the pointer 7 is at thedesired place on the scale which is regarded as providing for the properfocus for the object to be measured.

My attachment consists of a U-shaped frame having a bottom portion 23, atop portion 24, and an intermediate connecting portion 25. The topportion 24" is provided with a slot 26 in which a downwardly extendinglug 27 having an integral laterally extending cam member 28 is designedto slide. The lug is threaded to engage the threaded spindle 29 which ismounted in the upper portion of the frame as shown in Fig. 9. A tapecasing13 having the usual spring and locking device on the inside (notshown) and provided with a release button 13 is rigidly secured to theframe by a fastening device 30 and the reel of this tape casing orreceptacle is a prolongation of the spindle 29 as in the preferred formof the device. I i

In the use of this modified form the lens frame is pulled out until thepointer registers with the four foot mark on the scale or such mark aswould indicate the nearest distance which the camera can be placed fromthe object in order to have the lens in good focus for that distance.The attachment is now placed in position on the door in such a mannerthat the block or threaded lug 27 pulls out the tape to the object isjust behind the frame of the locking member 21. The cam member 28 is inthe dotted line position shown in Fig. 7 the tape or flexible memberbeing within the casing 13. The set screw 31 is now tightened so as tohold the attachment securely to the door 2*. Springs 32 (see Fig. 6) aresecured to some portion of the camera such as the brace members 33 atone end and the locking frame 21 at the other, thus exerting a tensionon the lens frame to which the locking device 21. is connected tendingto pull the lens inwardly.

. The flexible member or tape 15 is now pulled out and the threaded lug27 will begin to move toward the right in Fig. 7 and when four feet oftape has been pulled out the cam surface will be in the position shownin Fig. 7 in full lines so that further movement will permit the frameof the locking member 21 to be moved inwardly under the tension of thesprings 32*.

The flexible member 15 is moved out as far as the object, and the lensframe will move inwardly so that it is in proper focus for taking a viewof an object whose distance is equal to the length of the flexiblemember which has been pulled out from the reel or casing 13*. In Fig. 8I have shown the pointer 7 a as indicating a distance of ten feet. Theobject may be photographed and the lens will be at the proper focaldistance. The springs 32* may ,now be released and the clamping devicemay be removed by unscrewing the set screw 31*.

It will thus be seen that I have provided a device in which the mereextension of a flexible member such as a tape from the camera to theobject to be photographed will at once bring the camera into properfocus and that the proper focus may be maintained Within the limits ofthe camera.

I claim:

1. The combination Witha camera, of a casing carried thereby, a flexiblecoil carried by said casing and adapted to be unwound by pulling on oneend of the coil, and means for regulating the focusing of the camera inaccordance with the amount of the flexible coil which is unwound,

2. The combination with a camera having a lens adapted to be movedtoward and away from the light receiving surface of the camera, ofspring means for retracting the lens toward the light receiving surfaceof the camera, a movable member for regulating the amount of retractionof the lens, and means for actuating said movable member to permit theretraction of the lens for a predetermined distance.

3. The combination with a camera having a lens adapted to be movedtoward and away from the'light receiving surface of the camera, ofspring means for retracting the lens toward the li ht receiving surfaceof the camera, a movable member for regulating the amount of retractionof the lens, means for actuating said movable member to permit theretraction of the lens for a predetermined distance, said last namedmeans comprising a threaded spindle, a block having a threaded openingarranged'to receive said spindle and to be moved by the rotation of thespindle, and means secured to the end of the spindle for rotating thelatter.

4. The combination with a camera having a lens adapted to be movedtoward and away from the light-receiving surface of the camera, ofspring means for retracting the lens toward the light receiving surfaceof the camera, a movable member for regulating the amount of retractionof the lens, means for actuating said movable member to permit theretraction of the lens for a predetermined distance, said last namedmeans comprising a threaded spindle, a block having a threaded openingarranged to receive said spindle and tobe moved by the rotation of thespindle, and a flexible coil wound around one end of said spindle andadapted to rotate the spindle when one end of the coil is pulled out.

5. The combination with a camera, of a flexible coil secured thereto andadapted to be unwound by pulling on the end of the coil, and means forautomatically maintaining the focus of the camera upon a plane at rightangles to the axis of the lens and passing through the end of theflexible member in any position of the latter.

6. The combination with a camera, of a slidable lens frame, a carrierfor said lens frame movable in a direction parallel to the major axis ofthe lens, spring means for placing said carrier, under tension, a stopmember movable transversely of the axis of the lens and adapted toengage the carrier for regulating the position of the letter.

7. The combination with a camera, of a slidable lens frame, a carrierfor said lens frame movable in a direction parallel to the major axis ofthe lens, spring means for placing said carrier under tension, a stopmember movable transversely of the axis of the lens and adapted toengage the carrier for regulating the position of the latter, and meanscomprising a threaded spindle for causing the transverse movement ofsaid movable member.

8. The combination with a camera, of a slidable lens frame, a carrierfor said lens frame movable in a direction parallel to the major axis ofthe lens, spring means for placing said carrier under tension, a stopmember movable transversely of the axis of the lens and adapted toengage the carrier for regulating the position of the latter, meanscomprising a threaded spindle for causing the transverse movement ofsaid movable member, and a flexible coil wound carried by said casingand adapted to be unwound by pulling on one end of said flexible member,and'means for regulating the focusing of the .camera in accordance withthe amount of the flexible member which is unwoundn 10. A focusingattachment for cameras consisting of a revoluble drum adapted to bemounted on the camera, a flexible means wound on the drum, and meansactuated by the drum to automatically focus the camera by the unwindingof said flexible means.

11. A focusing attachment for cameras consisting of a revoluble drum, acord or tape wound thereon, reducing gear actuated by said drum, and acam controlled by said gearwhereby the unwinding of the cord or tapefrom the drum will cause automatic focusing of the camera.

12. The combination with a camera, of a casing carried thereby, flexiblemeans carried by said casing and coiled thereon and adapted to beunwound by pulling on one end, and-means for regulating the focusing ofthe camera in accordance with the amount of the flexible means which isunwound.

13. The combination with a camera and its lens-board, of a casingcarried by said camera, a spring drum mounted in said casing and havinga cord or tape coiled thereon, reducing gear actuated by said drum, andcam means actuated by said gear upon the unwindin' of the cord or tapeto actuate the lens-board and automatically focus the camera.

14. The combination with a camera having a hinged door carrying thebellows and lens frame, of a casing mounted on said 'be photographed,lens focusing mechanism acting on said lens operatively actuated by saidmember and controlled by the reach of said member to the object to.focus the lens on the object.

16. In a camera, the combination with a shiftable lens, a member adaptedto reach to the object to be photographed and lens shifting mechanismcontrolled by the length of said member extended between the camera andobject for setting said lens in focus relative to that object.

17. In a camera, a lens focusing device and a stretched member designedto reach to the object to be photographed, said member operativelyconnected to the focusing device and designed to maintain the lens infocus with the far end of said stretched member while in operativeposition.

18. In a camera, the combination with a shiftable lens carriage, meansacting on said carriage for focusing the lens, a pull member operativelyconnected to said means and designed to permit the lens to be moved intoprogressive focusing positions from its minimum range focusing positionas the free end of the pull member 1s drawn progressively away from thecamera.

19. In a camera, the combination with a shiftable lens carriage, meansacting on'said carriage for focusing the lens, a pull member operat velyconnected to said means and deslgned to permit the lens to be moved intoprogressive focusing position from its minimum range focusing positionas the free end of the pull member is drawn progressively away from thecamera, said means designed so that the unit distance traveled by theend of said pull member bears a variable relation to the retrograde ofsaid lens.

20. An automatic focusing attachment for cameras consisting of a springactuated drum having a cord or tape coiled thereon and carried by thecamera, the said coiled cord or tape serving when extended to the objectto be protographed to cause the focuscoiled means.

21. An automatic focusing attachment for cameras consistin of a casingcarried by the camera and exible coiled means carried. by the casing tocause when extended to the object to be photographed the focusing of thecamera by the movement away from the camera of the end of the flexiblecoiled means.

FRANK M. STEADMAN.

Witnesses:

SoLoN O. KEMON, LESTER A. STANLEY.

